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Hydrodynamics and OCM reaction performance in a bubbling fluidized bed reactor and a riser reactor

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Particuology 2024年第3期86卷 188-204页

作者： Min Cai Shuangzhu Kong sheng Chen Mengxi liu Chunxi Lu State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China China Special Equipment Inspection and Research Institute Beijing102249China

The reasonable reactor design is of great importance for increasing the C_(2) yield(C2H4 and C2H6)of the oxidative coupling of methane(OCM),and the OCM reactor should remove the heat released in reactions quickly and efficiently and minimize the consecutive reaction of ethylene to carbon *** fluidized bed reactor is characterized by excellent heat transfer,superior mass transport,and large handling capacity,while fewer studies focused on large-scale fluidized bed reactors for the OCM ***,large cold-model experiments and computational fluid dynamics simulations were conducted to investigate hydrodynamics and the OCM reaction performance in a large-scale bubbling fluidized bed(BFB)and a large-scale *** the BFB reactor,consecutive reactions of ethylene are acute because of the strong gas back-mixing,high solids holdup,and non-uniform solids *** the consecutive reactions of ethylene are negligible due to the plug flow structure and low solids holdup in the riser ***,both reactors can achieve isothermal operation for the OCM *** C_(2) selectivity of 45.4% and C_(2) yield of 21.1% are obtained in the riser reactor,increasing by 20.3% and 5.8% individually than that in the BFB *** study provides useful information and reference to the OCM reactor designandcommercialization.

关键词： Oxidative coupling of methane Bubbling fluidized bed reactor Riser reactor Hydrodynamics Isothermal operation

A NEW METHOD UTILIZED TO DETECT DNA SINGLE STRAND BREAK(NICK-TRANSLATION)

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Chinese Science Bulletin 1989年第13期34卷 1130-1133页

作者：刘杰杨胜利胥彬 Shanghai Institute of Materia Medica Academia Sinica

It is often needed to detect the DNA single strand break in biological studies. The four most frequently used methods are alkaline elution, alkaline sucrose gradient sedimentation, hydroxyapatite chromatography and nu... 详细信息

关键词： DNA single strand break nick-translation 10-hydroxyeamptothecin

Innovations in metallurgical and materials processes:advancing liquid theory and honoring ***-jie Guo's contributions to physical chemistry in metallurgy

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Journal of Iron and Steel Research International 2024年第1期31卷 1-2页

作者： Shuai liu Jing Guo Han-jie Guo School of Artificial Intelligence Beijing Technology and Business UniversityBeijing100048China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing(USTB)Beijing100083China

Spanning three decades,***-jie Guo's research group has dedicated itself to exploring the fundamental theories and practical applications of physical chemistry within the realm of *** under the assumption that molecul... 详细信息

关键词： chemistry liquid complexes

Multiple damage zones around hydraulic fractures generated by high-frequency pulsating hydraulic fracturing

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Petroleum Science 2024年第4期21卷 2688-2702页

作者： Yan Peng sheng-jie Wei Guang-Qing Zhang Da-Wei Zhou Chuang-Chao Xu School of Petroleum Engineering China University of Petroleum PetroChina Changqing Oilfield Company

Pulsating hydraulic fracturing(PHF) is a promising fracturing method and can generate a dynamic periodic pressure. The periodic pressure can induce fatigue failure of rocks and decrease initiation pressure of fracture. If the frequency of periodic pressure exceeds 10 Hz, the distribution of pressure along the main fracture will be heterogeneous, which is much different from the one induced by the common fracturing method. In this study, the impact of this special spatial feature of pressure on hydraulic fracture is mainly investigated. A coupled numerical simulation model is first proposed and verified through experimental and theoretical solutions. The mechanism of secondary fracture initiation around the main fracture is then discovered. In addition, sensitivity studies are conducted to find out the application potential of this new method. The results show that(1) this coupled numerical simulation model is accurate. Through comparison with experimental and theoretical data, the average error of this coupled model is less than 1.01%.(2) Even if a reservoir has no natural fracture, this heterogeneous distribution pressure can also cause many secondary fractures around the main fracture.(3) The mechanism of secondary fracture initiation is that this heterogeneous distribution pressure causes tensile stress at many locations along the main fracture.(4) Through adjusting the stimulation parameters, the stimulation efficiency can be improved. The average and amplitude of pressure can increase possibility of secondary fracture initiation. The frequency of this periodic pressure can increase number of secondary fractures. Even 6 secondary fractures along a 100 m-length main fracture can be generated.(5) The influence magnitudes of stimulation parameters are larger than ones of geomechanical properties, therefore, this new fracturing method has a wide application potential.

关键词： Tight reservoir Reservoir stimulation Numerical simulation Secondary fracture Fracture initiation

Hydrogen-rich surface of MoC catalysts for efficient CO_(2) hydrogenation induced by a coupled hydrogen donator

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Nano Research 2024年第8期17卷 7762-7767页

作者： Dong Xu Si-Yuan Xia Qi-Yuan Li jie-sheng Chen Xin-Hao Li School of Chemistry and Chemical Engineering Frontiers Science Center for Transformative MoleculesShanghai Jiao Tong UniversityShanghai 200240China

Direct CO_(2) hydrogenation offers an important strategy for promoting the global carbon balance,but high thermodynamic and kinetic stability of CO_(2) has restricted its applicability to only a handful of industrial ***,we introduce a proof-of-concept application of the electron-rich Pt surface to promote hydrogen donation for electron-rich MoC particles acting as hydrogen acceptors,thereby constructing hydrogen-rich surface of MoC active ***,the formed hydrogen-rich and electronrich surface could greatly decrease reaction activation energy to boost the efficient CO_(2) hydrogenation into formic acid over the MoC *** optimized MoC@NC/Pt-0.1(NC:nitrogen-doped carbon)catalyst exhibits a high turnover frequency(TOF)value of 1.2 h^(−1) at a lower temperature of 60℃and a TOF of 24.2 h^(−1) under standard reaction conditions widely used in the literature,exceeding 7 times of MoC@NC catalyst and surpassing the benchmark classical non-noble metal active center-based heterogeneous catalyst.

关键词： electron-rich Pt nanoparticles hydrogen donation hydrogen-rich MoC nanoparticles CO_(2) hydrogenation formic acid

Slicing capacity-centered mode selection and resource optimization for network-assisted full-duplex cell-free distributed massive MIMO systems

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Science China(Information Sciences) 2024年第1期67卷 203-220页

作者： jie WANG Jiamin LI Pengcheng ZHU Dongming WANG Hongbiao ZHANG Yue HAO Bin sheng National Mobile Communications Research Laboratory Southeast University 2. Purple Mountain Laboratories China Mobile Research Institute

Network-assisted full-duplex(NAFD) cell-free distributed massive multiple-input multipleoutput(MIMO) systems enable uplink(UL) and downlink(DL) communications within the same timefrequency resources,which potentially reduce latency by avoiding the overhead of switching UL/DL ***,how to choose UL/DL modes remains an important factor affecting system *** the dramatic increase in the number of users and access points(APs),massive access brings significant overhead in the mode ***,the different quality of service(QoS) among users also makes the effective utilization of resources *** one of the most promising technologies in sixth-generation(6G),network slicing enables the adaptive configuration of limited UL/DL resources through the resource isolation assisted NAFD ***,we propose a slicing capacity-centered *** this scheme,APs are motivated by slicing requirements and associated slices to form different *** mode selection and resource allocation are performed within each subsystem to reduce overhead and improve resource *** implement this scheme efficiently,a double-layer deep reinforcement learning(DRL)mechanism is used to realize the joint optimization of mode selection and resource *** results show that the slicing capacity-centered scheme can effectively improve resource utilization and reduce overhead.

关键词： network-assisted full-duplex network slicing mode selection resource optimization deep reinforcement learning

Iron-Catalyzed Reductive C(aryl)—Si Cross-Coupling of Diaryl Ethers with Chlorosilanes

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Chinese Journal of Chemistry 2024年第6期42卷 578-584页

作者： Pei liu Baowei Wu Xuefeng Cong jie Kong School of Chemistry and Chemical Engineering Northwestern Polytechnical UniversityXi'anShaanxi710072 China Institute of Molecular Plus Department of Chemistry and Haihe Laboratory of Sustainable Chemical TransformationsTianjin University92 Weijin RoadTianjin300072 China

The reductive cross-coupling between C(aryl)—O and Si—Cl bonds is of much importance as a valuable strategy for the construction of C(aryl)—Si bonds but has remained a great ***,we report a reductive cross-coupling of diaryl ethers and chlorosilanes via strong electrophilic C(aryl)—O and Si—Cl bonds cleavage by iron catalysis,which constitutes an efficient protocol for the synthesis of a range of functionalized *** combination of low cost FeCl2 as the precatalyst and iPrMgCl as the reductant shows high activity in the successive cleavage of unactivated C(aryl)—O bonds of diaryl ethers and strong electrophilic Si—Cl bonds of chlorosilanes,allowing their cross-coupling in a reductive *** low-valent iron species generated in situ by reduction of FeCl2 with iPrMgCl was proposed,which prefers to initially cleavage the C(aryl)—O bond of diaryl ethers with the chelation help of an o-amide auxiliary.

关键词： Cross-coupling Diaryl ethers Chlorosilanes C—O bond cleavage Iron catalyst 3d transition metals Selectivity Regioselectivity

High-temperature oxidation resistance of Si-coated C/SiC composites

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Rare Metals 2024年第9期43卷 4566-4572页

作者： jie Xiao Hua-Yue Zhang sheng-Kai Gong Hui-Bin Xu Hong-Bo Guo School of Materials Science and Engineering Beihang UniversityBeijing 100191China Key Laboratory of High-Temperature Structure Materials and Protective Coatings(Ministry of Industry and Information Technology) Beihang UniversityBeijing 100191China

In this paper,Si coatings were sprayed onto C/SiC composite substrates by atmospheric plasma spraying(APS).The high-temperature oxidation behavior of the substrate and coating at temperatures of 1100 and 1300℃was also *** C/SiC ceramic matrix composite will be damaged seriously and even failed due to the oxidation of carbon fibers in *** Si coating effectively improved the oxidation resistance of the C/SiC substrate in the high-temperature oxidation *** effect of the thickness of the Si coatings on the oxidation resistance was *** 150-μm coating is proved to enable the substrate to have the lowest oxidation weight loss and the best oxidation resistance after static oxidation for 5 h.

关键词： Ceramic matrix composites(CMCs) Carbon fiber Si coating Oxidation Plasma spray

Regression Method for Rail Fastener Tightness Based on Center-Line Projection Distance Feature and Neural Network

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 356-371页

作者： Yuanhang Wang Duxin liu sheng Guo Yifan Wu Jing liu Wei Li Hongjie Wang Robotics Research Center School of MechanicalElectronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China China Construction Industrial&Energy Engineering Group Co. Ltd.Nanjing 210023China

In the railway system,fasteners have the functions of damping,maintaining the track distance,and adjusting the track ***,routine maintenance and inspection of fasteners are important to ensure the safe operation of track ***,assessment methods for fastener tightness include manual observation,acoustic wave detection,and image *** are limitations such as low accuracy and efficiency,easy interference and misjudgment,and a lack of accurate,stable,and fast detection *** at the small deformation characteristics and large elastic change of fasteners from full loosening to full tightening,this study proposes high-precision surface-structured light technology for fastener detection and fastener deformation feature extraction based on the center-line projection distance and a fastener tightness regression method based on neural ***,the method uses a 3D camera to obtain a fastener point cloud and then segments the elastic rod area based on the iterative closest point algorithm *** component analysis is used to calculate the normal vector of the segmented elastic rod surface and extract the point on the centerline of the elastic *** point is projected onto the upper surface of the bolt to calculate the projection ***,the mapping relationship between the projection distance sequence and fastener tightness is established,and the influence of each parameter on the fastener tightness prediction is ***,by setting up a fastener detection scene in the track experimental base,collecting data,and completing the algorithm verification,the results showed that the deviation between the fastener tightness regression value obtained after the algorithm processing and the actual measured value RMSE was 0.2196 mm,which significantly improved the effect compared with other tightness detection methods,and realized an effective fastener tightness regression.

关键词： Railway system Fasteners Tightness inspection Neural network regression 3D point cloud processing